I wear my buff for cool temperatures, 50-60. It is pretty handy, when it starts cold I like it as a beanie over my ears, then I can make it a headband or just push it off my ears. Fits well under my medium Giro helmet but I do have to adjust the back.

When it gets blustery I wear my Cannondale Alpaca Wool beanie. It is so warm and wicks very well, I just love it. I even travel with this one because it is so comfortable for wearing out and about. It was a life saver when I visited California in February, fits in a pocket well, warm and doesn't get stinky.